Problem: Evaluate the following expression when $a = 9$ and $b = 9$. $6$ $a$ $ + 3$ $b$ $ - 10$
Substitute $9$ for ${a}$ and $9$ for ${b}$ $ = 6{(9)} + 3{(9)} - 10 $ $ = 54 + 27 - 10 $ $ = 71$